The authors gave the edge to the Celestron Ultimas and Tele Vue Plossls as "consistently a trace sharper and more contrasty than the rest."

"The Barlow Lens: More Power to You," by Dickinson, Terence, Sky & Telescope, July 1997, pages 59-62.

A review of Barlow lenses from Celestron, Edmund Scientific, Lumicon, Meade, Orion, Tele Vue, University Optics, and Vernonscope. The author gave the edge to the Celestron 2X Ultima, Tele Vue 2X and 3X, and Vernonscope 2.4X Dakin.